NAME

DESCRIPTION

This document describes differences between the 5.17.9 release and the 5.17.10 release.

If you are upgrading from an earlier release such as 5.17.8, first read perl5179delta, which describes differences between 5.17.8 and 5.17.9.

Security

Hash iteration randomized per hash variable

Every hash has its own iteration order, which should make it much more difficult to determine what the current hash seed is.

Incompatible Changes

Explicit rules for variable names and identifiers

Due to an oversight, length-one variable names in 5.16 were completely unrestricted, and opened the door to several kinds of insanity. As of 5.18, these now follow the rules of other identifiers, in addition to accepting characters that match the \p{POSIX_Punct} property.

There are no longer any differences in the parsing of identifiers specified as $... or ${...}; previously, they were dealt with in different parts of the core, and so had slightly different behavior. For instance, ${foo:bar} was a legal variable name. Since they are now both parsed by the same code, that is no longer the case.

[ List each incompatible change as a =head2 entry ]

Deprecations

PL_sv_objcount

This interpreter-global variable used to track the total number of Perl objects in the interpreter. It is no longer maintained and will be removed altogether in Perl 5.20.

New Diagnostics

New Warnings

Use of @*, &*, ** or %* is now deprecated, and will generate a compile time warning, enabled by default. In future such code will fail to compile with a syntax error. Removing these variables, along with $*, will permit future syntax additions.

Changes to Existing Diagnostics

The warning that use of $* and $# is no longer supported is now generated for every location that references them. Previously it would fail to be generated if another variable using the same typeglob was seen first (e.g. @* before $*), and would not be generated for the second and subsequent uses. (It's hard to fix the failure to generate warnings at all without also generating them every time, and warning every time is consistent with the warnings that $[ used to generate.)

Internal Changes

The new copy-on-write mechanism that was introduced in 5.17.7 has now been disabled by default, since it was felt that there were too many rough edges for the 5.18 release. It is expected that it will be enabled by default for 5.20.

This change also re-enables PL_sawampersand by default.

It can be enabled in a perl build by running Configure with -Accflags=-DPERL_NEW_COPY_ON_WRITE, and we would encourage XS authors to try their code with such an enabled perl, and provide feedback. XXX need blurb, e.g. a reference to a new section in perlguts or perlxs explaining how XS authors should handle COW strings.

Selected Bug Fixes

Fix two crashes in the debugger when using Frame=2 or autotrace. These are [perl #116769] and [perl #116771].

Acknowledgements

Perl 5.17.10 represents approximately 4 weeks of development since Perl 5.17.9 and contains approximately 77,000 lines of changes across 440 files from 42 authors.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.17.10:

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

Reporting Bugs

If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at http://rt.perl.org/perlbug/ . There may also be information at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to perl5-security-report@perl.org. This points to a closed subscription unarchived mailing list, which includes all the core committers, who will be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.

SEE ALSO

The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.

Module Install Instructions

To install perldelta, simply copy and paste either of the commands in to your terminal

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